Time delay switch



Feb. 5, 1957 c. M. DUNLAP TIME DELAY SWITCH 2 Sheets-Sheet 1 Filed Dec.10, 1954 PUMP VALVE SOLENOID INVENTOR' CHARLES M. DUNLAP BY ATTORNEYSFeb. 5, 1957 c. M. DUNLAP TIME DELAY SWITCH 2 Sheets-Sheet 2 Filed Dec.10, 1954 a MW INVENTOR. CHARLES M. DUNLAP ATTORNEYS TIME DELAY SWITCHCharles IV. Dunlap, Mansfield, Ghio Application December 10, 1954,Serial No. 474,493

18 (Ilaims. (Cl. 68--24) This invention relates to time delay switches,and particularly to switching or controlling mechanism for causing arotating member to be driven at low speed after a period of high speedoperation under conditions of excessive vibration and to thereafterreestablish high speed drive in response to a predetermined amount ofrotation of the member at low speed.

The invention relates particularly to a control switch mechanism forautomatic washing machines having a spin dry cycle during which water isremoved from the clothes by a centrifuging step. it often happens thatthe clothes in the machine are not evenly distributed in the rotor atthe commencement of the centrifuging cycle and thus unduly largevibrations are induced in the machine. If. the magnitude of thevibrations exceeds a certain predetermined value, there is danger ofdamage to the machine and it is therefore desirable to discontinue thecentrifuging cycle and to rotate the rotor at low speed until theclothes have redistributed themselves in such a way that centrifugingmay be continued without excessive vibrations.

in general, the invention is embodied in a control switch mechanismmounted adjacent a part of the rotor, particularly a tub resilientlymounted in the machine housing and enclosing the rotor basket. Thecontrol mechanism includes a rotary element normally set in a fixedposition but subject to excessive vibrations between the tub and housingto partially rotate the element with resultant translation thereof.Translation of the element causes a switching mechanism to establish lowspeed drive to the rotor or basket of the washing machine and that sametranslation places the rotary element in position to be engaged by therotor of the machine and rotated thereby in a step-by-step manner toeffect translation back to its original position wherein high speeddrive to the rotor is again established. In addition to the specificconstruction, the principal feature of this invention resides in thearrangement wherein the rotor or basket itself, being driven at lowspeed, constitutes the timing mechanism for reestablishing high speeddrive after the basket has made enough revolutions at low speed toeffect redistribution of the clothes therein.

It is therefore an object of this invention to provide a controlmechanism that is economical to produce and highly eflicient andreliable in operation.

A further object of this invention is to provide a control mechanismhaving a timing feature but wherein no separate timing" device isemployed.

it is still another object of this invention to provide a controlmechanism for a washing machine that is effective in response toexcessive vibrations during a centrifuging cycle, to establish low speeddrive to the machine basket and to thereafter be responsive to rotationof the basket a predetermined amount to again establish high speed drivefor centrifuging.

Further and additional objects and advantages will become apparent tothose skilled in the art as the descripte States atent 0 Id tionproceeds in connection with the accompanying drawings, wherein:

Fig. l is a vertical sectional view through a washing machine embodyingthe present invention;

Fig. 2 is a vertical sectional view taken substantially along the line2-2 of Fig. 1;

Fig. 3 is a fragmentary sectional view on an enlarged scale, takensubstantially along the line 33 of Fig. 2;

Fig. 4 is a vertical sectional view taken substantially along the line44 of Pig. 3;

Fig. 5 is a vertical sectional view taken substantially along the line55 of Fig. 4;

Fig. 6 is a schematic wiring diagram illustrating one possible circuitarrangement incorporating the present invention; and

Pi g. 7 is a fragmentary view of a portion of the mechanism of Fig. 4but illustrating a modified form of pawl.

The present invention is particularly applicable to washing machines andan automatic washing machine is shown and described herein, but it is tobe understood that the invention may be applied to other mechanismsalso.

The washing machine shown in Figs. 1 and 2 comprises an outer housing 2which may be supported on suitable feet 4 and which is provided with anaccess door 6. An imperforate tub 8 is mounted in the housing 2 by meansof a resilient supporting arrangement indicated generally at it andtension springs 12. The supporting arrangement ll? is of conventionalconstruction and need not be further described in detail except to saythat it sup ports the major portion of the weight of the machinemechanism but permits vibration of the tub 3 about an axis generally inthe arrangement ill. The tension springs 12 partially support the weightof the tub and related mechanism and are effective to normally hold thetub in a centralized position. Suitable bellows or other sealing means14 provide a water-tight seal between a central opening 16 in the frontwall of a tub 8 and the access doorway in the housing 2. The bellows 14effect the desired sealing without interfering with vibratory movementsof the tub.

A suitable drive motor 18 is mounted on the tub 8 and drives, through adrive pulley 20 and belt 22, to a sheave or pulley 24 secured to shaft26. The shaft 26 is journalled in suitable bearin s 28 carried by thetub 8 and rotary basket 30 is fixed to the inner end of the shaft 26within the tub 8. The basket 39 is provided with an access opening 32 inalignment with the opening 16 in tub 8 and the access door 6 of thehousing 2. The motor 18 includes a housing 34 in which a suitablevariable transmission is mounted to effect different speed drives fromthe motor to the basket Ell. The gearing in the housing 34 and thecontrols therefor are conventional and need not be further described.The motor 18 also includes an integral pump 36 for pumping water fromthe tub 8.

Fig. 6 schematically indicates a wiring diagram wherein switches 38 arecam-actuated by a motor driven cam (not shown) to sequentially effectthe usual cycles of operation common to automatic washing machines; Thewater switch is of a conventional type actuated by air pressure bellowsand connected by a tube to the tub sump. When the tub is being filled,the switch is actuated by the pressure of the head of water. It resetswhen the pump 36 relieves the pressure. Such switches and their use inwashing machines are well known and will not be further described.

The drive from the motor 13 to the rotor or basket 30 is at a speeddetermined by the condition of solenoid 40. When solenoid 49 isenergized, the variable transmission in housing 34 is actuated toestablish a high speed drive to the basket to spin the clothes thereinand extract most of the moisture by centrifugal force. When the solenoidis deenergized, the transmission normally returns to the low speed driveutilized during the Washing cyole. The time delay switch 42 controlsenergization .of the solenoid 40 and the means for actuating switch 42constitute the means of the present invention.

The washing machine construction and the general features of the controlcircuit therefor are conventional in the art and donot constitute partof the present invention.

'It'is tobe understood that any equivalent washing machine'structure orcircuit arrangement may be employed with equal facility.

The switch 42 is shown in greater detail in Figs. 1 through 5 andconsists of a pair of spring arms 44 mounted at one end on a bracket 46secured to the rear wall of the tub 8. The arms 44 are insulated fromeach other and from the bracket 46 by insulating material 47 (Fig. 4).Each of the arms 44 is suitably connected to conductors 48 and 50,respectively, constituting part of the wiring circuit shown in Fig. 6.Adjacent their free ends the arms 44 carry contact elements 52 and thearrangement is such that the arms 44 normally tend to assume a posi'tionwherein the contacts 52 are separated, thus deenergizing solenoid 40. Asstated, the arms are resilient and their free ends may be displaced asshown in Fig. 4

'to a'position wherein the contacts 52 engage each other to energize thesolenoid 40.

A spring arm 54 is mounted at one end thereof to the flange 56 ofbracket 46 whereby the arm 54 constitutes a resilient cantilever supportfor a cam disc 58. The arm 54 is further provided with an insulatedprojection or boss 60 arranged adjacent the outer ends of the switcharms 44. The spring arm 54 is normally biased in an upward direction sothat it normally tends to move upwardly to permit contacts 52 toseparate and open the solenoid circuit. The spring arm 54 is bifurcated(see Fig. 3) to provide arms 62 which are formed at their outer ends asloops 64 constituting bearings for the ends of a shaft 66 to which thecam disc 58 is rigidly secured. The cam disc 58 is provided with agenerally circular periphery, the major portion of which is trulycircular and concentric to the shaft 66 but which is provided with asingle lobe 68 of limited angular extent and projecting outwardly fromthe circular periphery by an amount at least: equal to the amount ofmovement'necessary to be imparted to the outermost end of arm 54 toeffect opening and'icilosing of switch 42.

The rear wall of the tub 8 has a further bracket 70 fixed thereon andwhich has an outwardly extending flange 72 projecting outwardly over'theperiphery of the cam 58. The bracket 70 is so positioned that theresilient characteristics of the arm 54 hold the periphery of cam disc58 in contact with the lower. face of flange 72 at all'times. The partsare so proportioned and positioned that when the cam disc 58 is in thefull line position of Fig. 4 with the tip of its lobe 68 engaging flange72, the arm'54 is pushed downwardly far'enough to effect closing ofswitch 42. When the cam disc 58 is rotated through asmafll angle toremove its lobe 68 from contact with the'flange 72, and permit thecircular portion of the cam periphery to engage that flange, the arm '54is permitted to move upwardly to the dotted line position of Fig. 4 toopen the switch 42.

The cam disc 58 is further provided with laterally extending ears 74.The ears 74 are angularly spaced about the shaft.66 and, in the formsh0wn,tsix such ears are provided. The ears 74 extend laterally of thedisc 58 inwardly of the cam periphery thereof.

The housing 2 supports a bracket 76 having an inwardly extending flange78 extending inwardly to a position in line with the lowermost ear 74 ofthe cam disc but laterally displaced thereof in a direction parallel tothe rear wall of the housing 2. Figs. 3 and 4 clearly show therelationship thus described. The parts are so positioned 8 does notvibrate suflicienttly to engage the lowermost ear 74 with the edge offlange '78. In the event the clothes in the basket 30 are so unevenlydistributed that centrifuging operation causes excessive vibration ofthe tub 8, the tub and, therefore, disc 58 which is mounted thereon,will move laterally a sufficient distance to not only engage thelowermost ear 74 with the adjacent edge of flange 78, but to move asufiiciently greater distance to cause the flange 78 to rotate the cam58 from the dead-center full line position shown in Fig. 4 so that theforce of the biased spring 54 holding the cam lobe 68 against flange 72is exerted on the slope of the lobe, thus rotating the cam 58 to thedotted line'position. Thus, excessive vibratory movement of the tub 8will cause the switch 42 to open the drive from motor 18 to the basket30 will, as a result, be reduced from the high speed drive to arelatively low speed. During the low speed drive, the clothes in basket30 may tumble and redistribute themselves in a more uniform arrangement.As shown, the bracket 76 is mounted on the housing 2 by means of boltsor screws 77 passing through slots 79 in bracket 76 whereby the bracketmay be adjusted to the desired position.

A bracket 80 (see also Fig. 5) mounted on the inner face of the sheave24 is provided with a pawl 82 pivoted thereto on an axis 84. A spring 86is secured to the bracket 80 by suitable means such as bolts 88 andengages an upwardly extending finger 90 of the pawl 82 to hold thatfinger against vertical flange 92 of bracket 89. The lowermost portionof the pawl 82 comprises a finger 94 extending downwardly and forwardlyfrom the axis 84. The pawl 82 may 'thus be rotated from the normalposition shown to a position wherein the rearmost edge 96 of finger 94engages the flange 92 with the lower arm of the pawl extendingdownwardly in the position indicated by dot-ted lines in Fig. 4. Thedotted line are A indicates the path of travel of the tip of pawl 82when in its normal position shown, whereas the dotted are 8 indicatesthe path of travel of the tip of the pawl 82 when swung about its axis84 to the dotted line position. As is clearly evident from Fig. 4, whenthe cam disc 58 is in position with its lobe 68 bearing against thefixed flange 72 of bracket 70, the cam disc itself is pushed downagainst the action of spring arm 54 to such position that its cars 74lie outside the are A. Thus, the sheave 24 and the basket 30 may rotatecontinuously without the pawl 82 engaging the ears 74 as long as the camdisc remains in the described position. When excessive vibra tions causethe flange 73 to partially rotate the cam disc 58, the ear 74 shown infull line at C will be moved to the dotted line position C wherein itsupper edge crosses the are A in position to be engaged by the tip ofpawl 82. When pawl 82 engages the ear in position C the pawl isswungiabout its axis 84 to the dotted line position and is effective topush the ear at C to about the position identified'at D whereupon thetip of the. pawl passes oif the upper edge'of the ear 74 near position Dafter having rotated the cam disc through a portion of one completerotation. During this interval the circular portion of the cam peripheryremains in contact with the flange 72 and the next succeeding ear '74also extends across the are A to be engaged by the pawl 82 after thebasket has made another revolution at low speed. Thus, the low speedrotation of the sheave 24 will cause the cam disc 58 to rotate in astep-by-step manner until its lobe 68 is again brought into contact withflange 72, at which time the cam disc will be pushed downwardly to suchan extent that its cars 74 lie outside the are A and no further rotationis impanted thereto by'the pawl 82. At the same time the spring arm 54is pushed downwardly and closes switch 42 to re-establish high speeddrive to the basket. In the form shown, the basket 30 must rotatethrough six complete revolutions at low speed beforehigh speed isre-established and in that time the {:3 u clothes 'will haveredistributed themselves. The illustrated embodiment, however, is merelyillustrative of the invention and it may be found in many instances thatonly six complete revolutions of the basket 30 at low speed are notsufiicient to redistribute the clothes, in which event it iscontemplated that a greater number of ears 74, or their equivalents, beprovided so that the basket rotates a greater number of times beforehigh speed operation is re-established.

In some instances the basket 8 and its contained clothes may be of suchweight and inertia and/ or may be operated at such high speed during thecentrifuging cycle that the mere opening of the contacts 52 andre-establishment of low speed drive will not in itself immediatelyreduce the speed of rotation of the basket 8. In such instances theinertia of the basket and its contents cause it to continue rotating athigh speed for an appreciable length of time after cam 58 is moved tothe dotted line position of Fig. 4, during which time the sheave 24 maymake several complete turns. pawl 82 would advance the cam 58 and highspeed drive could thus be re-established even before the basket 8 slowsdown to a low enough speed to redistribute the clothes. In such casesthe modified pawl construction shown in Fig. 7 may be employed.

In Fig. 7, elements identical to those shown in Fig. 4 are identified bythe same reference characters. The bracket 80 of Fig. 7 is the same asbracket 89 of Fig. 4 except that its flange 92' is provided with a slotor opening 1 30. The lowermost end of the slot 100 terminates above thelower end of flange 92, the lower part of which defines a stop abutment102. The pawl 104 is pivoted to bracket 80' at 84 with it plane ofpivotal movement extending through slot 100. The forward edge of pawl104 is formed with two surfaces 106 and 108 angul-arly arranged todefine a notch or depression having its apex generally opposite thepivot 84. Spring 86 is biased to normally urge its free end toward thepivot 84 into engagement with both surfaces 136 and 108, as shown infull lines in Fig. 7, and thereby normally hold pawl 104 with itsoutermost end lying on are A. The innermost part of pawl 104 extendsthrough slot 100 and is formed to define a relatively heavy weightelement 110 rearwardly of pivot 34. The element 110 is further formedwith an abutment surface 112. Thus, pawl 104 may rotate counterclockwise(as seen in Fig. 7) until its abutment urface 112 engages stop abutment102, as indicated by dotted outline B, such rotation being opposed bythe end of spring 86 acting on surface 106. The pawl 194 may also berotated clockwise from the full line position of Fig. 7 to dotted lineposition F with its rear edge engaging abutment stop 102 and itsoutermost tip lying on are B.

The strength of spring 86 and the weight of element 110 are so relatedthat centrifugal force acting on weight 110 rotates pawl M4 to theposition shown at B when sheave 24 rotates at speeds above apredetermined value. Preferably that predetermined speed isapproximately the low speed of the machine or only a little above thatspeed.

At the start of a centrifuging cycle, the pawl 104 pivots to theposition at E (Fig. 7) with its outer end positioned inwardly of are A adistance such that the pawl will not engage ears 74 of cam 58 even ifthe cam is moved to the dotted line position of Fig. 4 by excessivevibration of the basket and the pawl remains in that position as long asthe basket 8 continues to rotate at high speed. When the basket slowsdown to a speed approaching its low speed, spring 86 will overcome thecentrifugal force on weight 11% and rotate pawl 1M back to the full lineposition of Fig. 7 where its outer end is on are A and in position toengage the ears 74 of disc 58. Upon each engagement of the pawl 104 withan ear 74, the pawl moves to position F to advance cam disc 58 one stepand then spring 86 returns it to the full line position of Fig. 7, whichcorresponds to the full line position At each such turn the L 6 of pawl82 of Fig. 4. Thus, the step-by-step resetting of cam disc 58 does notstart until the basket slows down to a low speed and ample time isprovided for redistribution of the clothes before high speed drive isagain established.

The specific embodiment-s shown and described herein are merelyillustrative of the invention, which is not limited thereto. It is to beunderstood that many other modifications may be resorted to within thescope of the appended claims.

l claim:

l. in a device of the class described; a frame, a rotary member, neanssupporting said rotary member for rotation thereon, said supportingmeans being mounted on said frame for movement relative thereto inresponse to rotational unbalance of said rotary member, drive means forrotatin said rotary member, control means for said drive means foreffecting either hi h speed or low speed rotation of said rotary member,a switch for actuating said control means, a switch-operating membermovably mounted on said supporting means for movement to a firstposition wherein said switch is operated to establish high speed driveand to a second position wherein said switch is operated to establishlow speed drive, means responsive to movement of predetermined magnitudeof said supporting means relative to said frame during high speed drivefor moving said switch-operating member to said second position, andmovable means arranged to be moved by rotary motion of said rotarymember a predetermined amount at low speed for moving saidswitchoperating member to said first position.

2. A device as set forth in claim 1 wherein said switchoperating membercomprises a rotary element having projections thereon, one of saidprojections being engageable with means fixed on said frame for movingsaid switch-operating member from said first position toward said secondposition.

3. A device as set forth in claim 1 wherein said switchoperating membercomprises a rotary element having projections thereon, one of saidprojections being engageable with means fixed on said frame for movingsaid switch-operating member from said first position toward said secondposition, and a pawl on said rotary member engageable with saidprojections successively when said rotary element is in said secondposition to rotate said rotary element and move said switch-operatingmember back to said first position.

4. in a. machine having a frame, a rotary member, supporting meansmovably mounted on said frame and rotatably supporting said rotarymember, drive means for rotating said rotary member, and control meansfor said drive means for establishing either high speed or low speedrotation of said rotary member; the improvement comprising: a switch onsaid supporting means for actuating said control means, a rotary cammounted for rotation and translation on said supporting means, said camengaging a portion of said supporting means whereby rotation of said camproduces translation thereof between a first and second positionthereof, means responsive to translation of said cam for opening andclosing said switch, means on said frame engageable with a portion ofsaid cam for rotating said cam sufficiently to effect translationthereof from said first position toward said second position in responseto a predetermined movement of said supporting means relative to saidframe, and means carried by said rotary member engageable with said camwhen said cam is in said second position and operable in response to apredetermined rotation of said rotary member to further rotate said camto effect translation thereof back to said first position.

3'. A machine as defined in claim 4 wherein said cam is provided withangularly spaced projections and wherein said means carried by saidrotary member comprises a pawl movable along a circular path spaced fromsaid projections when said cam is in said first position but 7engageable with said projections to rotate said cam when said cam is insaid second position.

6. A mechanism having a support, a member rotatably mounted on saidsupport, drive means for rotating said member, control means for saiddrive means mounted on said support, said control means being effective,when actuated to a first condition, to establish a high speed drive tosaid member and, when actuated to a second condition, to establish alower speed drive to said member, a control element, means mounting saidcontrol element for rotation and translation on said sup port, meansresponsive to rotation of said control element to efiect translationthereof between a first and second position, means responsive tomovement of said element to said first position for actuating saidcontrol means to said first condition and responsive to movement of saidelement to said second position for actuating said control means to saidsecond condition, means normally biasing said control element to saidfirst position, means responsive to a predetermined magnitude ofrotational vibration of said member for rotating said element to efiecttranslation'thereof from said first to said second position, andrestoring means driven by siad member to further rotate said element toeit'ect translation thereof back to said first position.

7. in a washing machine or the like having a housing, a tub mounted insaid housing for vibratory movement therein, a rotor journalled in saidtub, drive means for rotating said rotor at either high or low speed,movable control means for said drive means movable in response toexcessive vibratory movement of said tub when said rotor is driven athigh speed for establishing low speed drive from said drive means tosaid rotor, and means rendering said control means thereafter movable inresponse to rotation of said rotor to reestablish high speed drivethereto after a predetermined amount of rotation thereof at low speed.

8, A machine as defined in claim 7 wherein said rotor is provided with arestoring element rotatable therewith along a predetermined circularpath and wherein said control means includes a device movably mounted onsaid tub for movement between a low-speed position adjacent said pathand a high-speed position remote from said path, said device havingmeans thereon positioned in the circular path of said restoring elementwhen said element is in said low-speed position and arranged to be movedby said restoring element to said high-speed position wherein saidlast-named means is removed from said path.

9. A machine as defined in claim 8 including a fixed element on saidhousing engageable with said last-named means upon excessive vibrationof said tub to move said device to said low-speed position.

10. A control switch mechanism for the drive means ofa machine having arotor journalled on a support and drive means for rotating said rotor atdifferent speeds, said switch mechanism comprising; a spring arm mountedat one end on said support, a cam disc journalleo on the other end ofsaid arm, said cam disc being of uniform radius throughout the majorportion of its periphery an having aperipheral undulation of limitedangular extent, a fixed abutment on said support, said spring arm beingbiased to hold the periphery of said cam disc against said abutment, aplurality of angular-1y spaced projections extending laterally from saiddisc, a pawl carried by said rotor for rotation therewith along a pathadjacent said disc, at least one of said projections lying in said pathwhen the portion of said cam disc periphery oi uniform radius is inengagement with said abutment, the radial extent of said undulationbeing such that all said projections are removed from said path whensaid undulation engages said abutment, and a control switch actuable bymovement of said spring arm in response to rotation of said cam disc.

11. A control switch mechanism as defined in claim 10 wherein saidundulation is a lobe of greater radius than the major portion of saiddisc periphery and wherein said spring arm urges said disc in adirection toward said path.

12. A control switch mechanism as defined in claim 10 wherein saidprojections comprise tabs extending laterally from one side of said discradially inwardly of the periphery thereof.

13. A control switch mechanism as defined in claim i0 wherein aid pawlis pivotally mounted on said rotor on axis eccentric to the rotor axis,stop means limiting pivotal movement of said pawl between first andsecond positions, the outermost end of said pawl being farthest from theaxis of said rotor in said second position, and means norn ally biasingsaid pawl to said first position, the journal aAlS of said disc beingsubstantially parallel to said rotor axis.

14. A control switch mechanism as defined in claim 12- including anelement movable relatively to said support and into engagement with oneof said projections to partially rotate said cam disc in response toexcessive rotational vibration in said rotor.

15. A'rnachine as defined in claim 4 wherein said cam is provided withangularly spaced projections and wherein said means carried by saidrotary member comprises a pa A l normally movable along a first circularpath spaced from said projections when said cam is in said firstposition but engageable with said projections to rotate said cam whensaid cam is in said second position, and centrifugal means responsive tothe speed of rotation of said rotary member and arranged to move saidpawl on said rotary member, in response to high speed rotation thereof,to move along a second circular path spaced from said projections evenwhen said cam is in said second position, and means cooperating withsaid centrifugal means for moving said pawl to said first circular pathwhen said rotary member rotates at or below a predetermined low speed.

16. A control switch mechanism for the drive means of a machine having arotor journalled on a support and drive means for rotating said rotor atdifferent speeds, said switch mechanism comprising; a spring arm mountedat one end on said support, a cam disc journalied on the other end ofsaid arm, said ca .1 disc being of uniform radius throughout the majorportion of its periphery and having a peripheral undulation of limitedangular ex tent, a fixed abutment on said support, said spring arm beingbiased to hold the periphery of said cam disc against said abutment, aplurality of angularly spaced projections extending laterally from saiddisc, a pawl pivotally mounted on said rotor, resilient means urgingsaid pawl to a first pivotal position wherein one end thereof moves withsaid rotor along a first path adjacent said disc, at least one of saidprojections lying in said path when the portion of said cam discperiphery of uniform radius is in engagement with said abutment, theradial extent of said undulation being such that all said projectionsare removed from said path when said undulation enga es said abutment, acentrifugal weight on said pawl arranged to pivotally swing said pawlagainst the action of said resilient means, during rotation oi": saidrotor above a predetermined speed, to position said one end of said pawlfor movement along a second path spaced from said projections even whenthe portion of said cam disc of uniform radius is in engagement withsaid abutment, and a control switch actuable by movement of said springarm in response to rotation of said cam disc.

17. A washing machine as defined in claim 7, including a centrifugallyresponsive element fixed relative to and rotatable with said rotor andarranged to render and maintain said controlmeans non-responsive torotation of said rotor at rotor speeds above a predetermined value.

18. A control switch mechanism as defined in claim predetermined valve,the outermost end of said pawl being removed from said path when in saidfirst position.

References Cited in the file of this patent UNITED STATES PATENTSAndrews et a1. Feb. 13, 1934 Hurley et a1 Feb. 16, 1943 Bassett Feb. 23,1943

